Gate oxide reliability concerns in gate-metal sputtering depostion process: an effect of low-energy large-mass ion bombardment

摘要

The effects of ion species/ion bombardment energy in sputtering deposition process on gate oxide reliabili ty have been experimentally investiaged. The use of oxenon (Xe) plasma instead of argon (Ar) plasma in tantalum (Ta) film sputtering deposition for gate electrode formation makes it possible to minimize the plasma-induced gate oxide damage. The Xe plasma process exhibits 1.5 times higher breakdown field and five times higher 50 -charge-to-breakdown (Q_BD). In the gate-metal sputtering deposition process, the physicla bombardment of energetic ion causes to generate hloe traps in gae oxide, resulting in the lower gate oxide reliability. The simplified model providing a better understanding of the empirical relation between the gate oxide damage and the ion-bombardment energy t o gate oxide in gate-metal sputtering deposition process is also presented.